Device for bringing up to speed a vehicle having an automatic transmission

ABSTRACT

Device for starting up a vehicle equipped with an automatic transmission provided between a drive shaft ( 1 ) and a driven shaft ( 2 ) in a transmission housing ( 7 ) with a planetary gear ( 4 ) with a first gear ( 14 ) coupleable with the drive shaft ( 1 ), with a second gear ( 13, 15 ) coupleable with the driven shaft ( 2 ) and with the third gear ( 12 ), wherein the third gear ( 12 ) is connectable with the transmission housing ( 7 ) via a start-up brake (S), of which the brake force is controllable.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention concerns a device for bringing up to speed avehicle equipped with an automatic transmission according to theprecharacterizing portion of claim 1.

[0003] 2. Description of the Related Art

[0004] Conventional multi-stage or multi-gear automatic transmissionsare conventionally provided, according to the state of the art, with astart-up or low gear device for providing the necessary start-uptranslation from the first gear of the transmission. In this state ofthe art, until now only two possibilities for realizing a start-updevice of this type have been known. On the one hand, there is used awet running start clutch (plate coupling), which operates without torqueamplification, and on the other hand there is used a Foettinger fluidtorque converter or hydrodynamic converter, which operates with a torqueamplification of greater than one.

[0005] A working example of the second mentioned variety is described ingreater detail below on the basis of FIG. 4. FIG. 4 shows a gearschematic of an automatic transmission according to the state of the artwith an upstream hydrodynamic converter as start-up device. Theautomatic transmission is an automatic six gear transmission asdescribed in detail in the translation of European patent EP 0 434 525B1, namely DE 690 10 472 T2. This automatic transmission as well as thearrangement described in this reference are simply referred to in thefollowing, by reference to the inventor Pierre Lepelletier, as aLepelletier automatic transmission. An automatic transmission 25according to Lepelletier in accordance with the illustrative embodimentshown in FIG. 4 includes a gear box 7, in which the following indicatedindividual components are provided, namely a drive shaft 1 as well as awork shaft 2, a simple input planetary drive 4 as well as a doubleoutput planetary drive 5, three clutches A, B and E as well as twobrakes C and B.

[0006] The input planetary drive 4 is comprised in known manner of a sungear 9, the planetary gear 13 held by the planet arm or, as the case maybe, planetary gear carrier 15 as well as the internal gear 14. Fromreference number 4 one can see that the sun gear 12, the planetary gearas well as the internal gear 14 engage in the conventional pair-wisemanner, namely the sun gear 12 is in engagement with the planetary gear13 and the planetary gear 13 with the internal gear 14.

[0007] The output planetary gear 5 is likewise comprised, in knownmanner, of a sun gear 16, an internal planetary gear 17 supported by theinternal planet arm or, as the case may be, internal planetary garcarrier 21, the external planetary gear 18 held by the external planetarm or, as the case may be, external planetary gear carrier 22 as wellas an internal gear 19. Further shown in this illustrative embodiment isa further sun gear 20.

[0008] From FIG. 4 one can additionally see that also the sun gear 16,the internal planetary gear 17, the external planetary gear 18 and thehollow gear 19 of the output planetary gear 5 engage in each other in aknown mode and manner. Thus the hollow gear 19 is in operativeengagement with the external planetary gear 18, the external planetarygear 18 is then in operative engagement with the internal gear 17 andthe internal gear 17 is in operative engagement with the sun gear 16.From FIG. 4 one can further see that the sun gear 20 is also inengagement with the external planetary gear 18.

[0009] The drive shaft 1 is connected with the internal gear 14 of theinput planetary drive 4. The sun gear 12 of the input planetary drive 4is connected fixed against rotation with the gear box or transmissionhousing 7. The planet arm 15 is on the one side connectable with the sungear 16 via the clutch A, on the other side also a connection with thesun gear 20 can be established via clutch B. The two planet armsconnected fixed against rotation with each other, inner planet arm 21and outer planet arm 22, of the output planetary drive 5 are on the oneside connectable fixed against rotation with the gear housing 7 via thebrake D, on the other hand via clutch E a connection with the driveshaft 1 can be established. Besides the possibility of connecting thesun gear 20 with the planet arm 15 of the input planetary drive 4 viathe clutch B, there exists beyond this the possibility to establish viabrake C a connection fixed against rotation with the gear housing 7.

[0010] It can further be seen from FIG. 4, that the internal gear 19 ofthe output planetary drive 5 is connected fixed against rotation withthe output shaft 2.

[0011] With the aid of the five shift elements, namely the threeclutches A, B and E as well as the two brakes C and D, it becomespossible by the selective pairwise engagement to effect varioustransmission relationships between the drive shaft 1 and the drivenshaft 2. There are possible a total of six forward gears, one brakedneutral position as well as one reverse gear. A detailed discussion aswell as the associated functional description can be found in theabove-mentioned reference DE 690 10 472 T2.

[0012] According to the state of the art in order to bring up to speed avehicle equipped with this automatic transmission 25 according toLepelletier there is provided upstream a start up device with ahydrodynamic converter 3 comprised of pump gear 8, turbine wheel 9 andguide wheel or idler 10. In concrete form the turbine wheel 9 isconnected with the drive shaft 1 of the above-described automatictransmission 25 according to Lepelletier. The idler wheel 10 isconnected in known mode and manner with the gear housing 7 via a freewheel 11. The pump wheel 10 is connected with the motor shaft M. Furtherin accordance with the state of the art a torque converter bridge overor intermediate lock-up clutch 6 is provided, which after completion ofthe bringing up to speed process makes possible a direct connectionbetween the motor shaft M of the internal combustion engine and thedrive shaft 1.

[0013] Although this type of arrangement has been basically provenitself, and in particular the realization of an automatic transmissionwith very small dimensions has been made possible, there remains theneed to further reduce the required construction space. Beyond this, ithas been found that a consequence a speed up device with a hydrodynamicconverter is a comparatively high fuel consumption.

SUMMARY OF THE INVENTION

[0014] The invention is thus concerned with the task, of providing adevice for bringing up to speed a vehicle provided with automatictransmission between a drive shaft and a driven shaft in a transmissionhousing, which on the one hand exhibits small space requirement andbeyond this makes possible greater fuel economy.

[0015] This task is solved by a device for bringing up to speed with thecharacterizing features of claim 1.

[0016] Advantageous embodiments and further developments of theinvention are set forth in the dependent claims.

[0017] The invention is based upon the idea, that instead of theconverter, one provides a planetary gear with at least three gears, ofwhich one, in certain cases via further gear stages, is coupleable withthe drive shaft and one, in certain cases likewise via further gearstages, is coupleable with the driven shaft and wherein the gear can beconnected via a start-up brake, of which the brake force iscontrollable, with the transmission housing of the automatictransmission.

[0018] The planetary gear is preferably a simple planetary gear with asun gear, a planetary gear and a internal gear, wherein for example theinternal gear can be coupled with the drive shaft, the planetary gearcan be coupled with the driven shaft via one or more gear stages and thesun gear is connectable with the housing via the above-mentionedstart-up brake. This variant offers advantages particularly in that,since it uses a planetary gear, it involves a known simple constructionwith small space requirement.

[0019] In accordance with the invention it is envisioned, that theplanetary gear is a component of the automatic transmission. Theadvantage of this variant is comprised therein, that according to thestate of the art a large number of automatic transmissions include thistype of planetary gear for changing gear ratio, preferably planetarygear sets.

[0020] It is frequently the case, that one gear of the above-mentionedplanetary gear present as a component of the automatic transmission isconnected fixed against rotation with the transmission housing. It isthus simply possible, to brake this fixed against rotation connectionand to establish a controllable coupling via a start-up brake.

[0021] It is envisioned in accordance with the invention that theplanetary gear, with which in accordance with the state of art one gearis connected fixed against rotation with the transmission housing, is apre-provided step-down or reduction gear or a pre-provided step-up orincrease gear of the automatic transmission. For realizing the inventionthis wheel is now connected with the transmission housing via theabove-mentioned start-up brake.

[0022] It is envisioned in accordance with the invention to implement adevice for starting up or bringing up to speed an admittedly knownautomatic transmission of the Lepelletier design. This variant has theadvantage of a particularly small construction size.

[0023] For illustration purposes reference is made to theabove-described embodiment in accordance with FIG. 4. An automatictransmission of this type includes—as has been described above indetail—a pre-provided step-down or reduction stage 27 in the form of aplanetary drive. This input planetary drive 4 includes, with referenceto the above description and the illustrative FIG. 4, a sun gear 12, aplanetary gear 13 held by the planet arm 15 as well as an internal gear14. This planetary gear is connected with the motor shaft M inaccordance with the state of the art on the input side via thehydrodynamic converter 3 or preferably via the converter bridging clutch6. The sun gear 12 of this input planetary gear box 4 is likewise inaccordance with the state of the art connected fixed against rotationwith the transmission housing 7. In accordance with the invention it ishowever envisioned, that the hydrodynamic converter 3 is dispensed withand the motor shaft M is directly connected with the drive shaft 1,whereby it is however also possible to provide there-between a rotationoscillation dampening device. Beyond this there is established, in placeof the fixed against rotation connection of the sun gear 12 with thetransmission housing 7, the above described inventive coupling of thesun gear 12 with the transmission housing 7 via a start-up brake. Thegear ratio of the first gear of the wide gear ratio automatictransmission in the Lepelletier design is sufficient for carrying outthe starting up processes even without a hydrodynamic torque enhancer.

[0024] It is envisioned in accordance with the invention, that thestart-up brake is a friction brake, of which the slip is controllable.The employment of a friction type start-up clutch of this type withcontrollable or adjustable slip in the vehicle automatic transmissionopens completely new and broad possibilities of the motor rotationalspeed adaptation, in order to increase fuel efficiency, without havingto sacrifice performance. The herein introduced idea of a broadening ofthe function of the Lepelletier automatic transmission satisfies allcurrent requirements of a modern vehicle transmission.

[0025] It is envisioned in accordance with the invention, to control thebrake force of the start-up brake in such a manner, that this is smallerat the beginning of the start-up process than at the end of the start-upprocess. Preferably the brake force is so controlled, that at thebeginning of the start-up process it essentially disappears, that is,that the start-up brake at the beginning at the start phase is opened,and that the brake after conclusion of the start-up process is arrestedand therewith establishes a fixed against rotation connection of the sungear to the transmission housing. Preferably the brake force issubstantially continuously increased from the beginning of the start-upprocess up to the end of the start-up process.

BRIEF DESCRIPTION OF THE DRAWING

[0026] Based upon the transmission according to the state of the artaccording to the illustrative embodiment shown in FIG. 4 there is shownin the drawing an automatic transmission with an inventive device forstart-up, which in the following will be described in greater detail.There is shown:

[0027]FIG. 1 a transmission diagram of an automatic transmission of avehicle according to Lepelletier with the inventive device for start-up;

[0028]FIG. 2 an RPM gear ratio diagram of the automatic transmission ofLepelletier with the inventive device for start-up according to FIG. 1—condition immediately after the beginning of the start-up process—

[0029]FIG. 3 an RPM conversion diagram of the automatic transmissionaccording to FIG. 1 —condition directly prior to ending the start-upprocess—

[0030]FIG. 4 an RPM conversion diagram of an automatic transmission ofLepelletier with hydrodynamic converter as start-up device —state of theart—

DETAILED DESCRIPTION OF THE INVENTION

[0031] The illustrative embodiment of an automatic transmission shown inFIG. 1 as a transmission schematic with the inventive device forbringing up to speed is based essentially upon the six harmonic stagedLepelletier type transmission described above and shown in FIG. 4.

[0032] The components of the automatic transmission 26 according toLepelletier are in accordance with the above-mentioned figure whereinthe identical reference numbers are used for the same or similarcomponents:

[0033] the drive shaft 1 continuously coupled on the input side to themotor via motor shaft M, the output drive shaft 2 continuously coupledwith the vehicle drive shaft F,

[0034] the upstream reduction gear 27, which is constructed as inputplanetary drive 4 with sun gear 12, planetary gear 13 and internal gear14,

[0035] the output planetary drive 5 with sun gear 16, internal planetarygear 17, external planetary gear 18, internal gear 19 and sun gear 20 aswell as

[0036] the pairwise engageable shift elements for shifting the gearsnamely clutch A, clutch B, clutch E, brake C and brake D.

[0037] For the concrete coupling of the individual components as well asfor the functioning of the automatic multi-gear transmission referenceis made to the above description as well as the examples in the thereinmentioned reference DE 690 10 472 T2.

[0038] In accordance with the invention there is now provided, in placeof the hydrodynamic converter 3 and the converter bridge clutch 6according to the state of the art, a controlled slip friction typestart-up clutch, referred to in the following as start-up brake S. Thisstart-up brake S is provided in place of the fixed against rotationconnection between the transmission housing 7 and the sun gear 12 of theinput planetary drive 4 and provides a controllable connection betweenthe transmission housing 7 and the sun gear 12 of the input planetarydrive 4.

[0039] The motor shaft M is now no longer connected with the drive shaft1 via the converter 3 or the converter bridging clutch 6, but rather ispreferably provided as a preferably direct fixed against rotation oroscillation dampened connection of the motor shaft M with the driveshaft 1.

[0040] The manner in which the inventive device functions for startingup an vehicle will be described in the following in greater detail onthe basis of FIGS. 2 and 3:

[0041] During the start-up process in the presently discussed automatictransmission 26 according to Lepelletier both the clutch A as well asthe brake D are closed, while the clutch B and E as well as the brake Care in the open position.

[0042] At the beginning of the start phase the start-up brake S isopened. By the rotation of the drive shaft 1 connected with the motorshaft M of the internal combustion engine the internal gear 14 or thereduction gear 27 provided upstream as input planetary drive 4 is drivenwith motor speed of rotation n_(M). The internal gear rate of rotationn₁₄ is thus identical to the motor rate of rotation n_(M).

[0043] The planet arm 15 of the input planetary drive 4 is connectedwith the drive shaft 2 and therewith with the vehicle drive shaft F viathe arrested clutch A and the output planetary drive 5. Since thevehicle is not moving, the value of the vehicle drive shaft rotationspeed n_(F) and therewith likewise the planet arm rotational speed n₁₅of the input planetary drive 4 is zero:

n_(F)=n₁₅=0

[0044] Since the reduction stage 27 is not an input planetary drive 4with a negative level of translation i_(o), in the described case thesun gear 12 rotates with the added on start-up brake S against the motordirection of rotation with the rotational speed

n _(s) =i _(o) ×n _(M).

[0045] Directly after the start-up the brake force of the start-up brakeS is increased. The sun gear 12 of the input planetary drive 4 is now nolonger completely freely moveable. This has the consequence, thatbesides the rotation of all gears 12, 13, 14 of the input planetarydrive 4 also a rotation of the planet arm 15 can occur.

[0046]FIG. 2 shows an RPM translation diagram of the automatictransmission 26 of Lepelletier with the inventive device for start-upaccording to FIG. 1 for the condition thereof directly after thebeginning of the start-up process.

[0047] The left side of the diagram represents the input planetary drive4, the right side of the diagram FIG. 2 represents the output planetarydrive 5. The verticals necessary for the graphic determination of therotation speed of the individual gears are shown in the figure using thereference numbers used in diagram of FIG. 1. Thus, the left lineassociated with the input planetary drive 4 in the form of a negative orminus gear is indicated with reference number 12 (sun gear), the centralline by reference number 15 (planet arm) and the right line by thereference number 14 (internal gear). Accordingly the output planetarydrive 5 in the form of a positive gear or gear box associated lines areindicated from left to right by the reference numbers 21 and 22 (innerplanet arm and outer planet arm), 19 (internal gear) and 16 (sun gear).

[0048] As can be seen from the diagram FIG. 2, the internal gear 14directly after the start-up of the vehicle rotates with the motorrotational speed

n₁₄=n_(M).

[0049] The speed of rotation n_(S) of the start-up brake S and therewiththe rotational speed n₁₂ of the sun gear 12 of the input planetary drive4 is slightly reduced as a result of the brake effect:

n _(S) =n ₁₂ <i _(o) ×n _(M).

[0050] (i_(o)=level of translation).

[0051] At the point of intersection of the degree of translation 23determined by the rotational speed n₁₄ of the internal gear 14 and therotational speed n₁₂ of the sun gear 12, with the vertical associatedwith the planet arm 15, there results the value of the planet armrotational speed n₁₅.

[0052] This planet arm rotational speed n₁₅ is transmitted to the sungear 16 of the output planetary drive 5 by means of the closed clutch A.The corresponding intersection with the vertical corresponding to thesun gear 16 can likewise be taken from the diagram FIG. 2. Since duringstart-up in the first gear the planet arms 21 and 22 of the outputplanetary drive 5 are not moveable for reason of the closed brake B, thedegree of translation 24 and therewith the internal gear rotationalspeed n₁₉ of the output planetary drive 15 can be determined. Theinternal gear rotational speed n₁₉ can be read from the intersection indiagram FIG. 2 of the translational degree 24 with the verticalcorresponding to the internal gear 19.

[0053] With increasing vehicle speed the start-up brake rotational speedn_(S) drops. The driven rotational speed, represented by the vehicledrive shaft rotational speed n_(F), thereby increases continuously. Thetorque T_(S) to be applied from the start-up brake S thereby correspondsto the factor of the reduced degree of the actual gear translation i_(o)of the transmission input torque T_(M):

T _(S) =T _(M) /i _(o).

[0054] The reduction stage of the input planetary drive 4 in theLepelletier system 26 generally exhibits a degree of translation i_(o)of approximately 2. Therefrom there results a reduced brake moment T_(S)reduced by a factor of i_(o)=2 compared to the transmission input momentT_(M).

[0055] Diagram FIG. 3 shows a rotation speed translation diagram of theautomatic transmission according to FIG. 1 in the case of an increasedbrake force of the start-up brake S, and therewith further reducedstart-up brake rotation speed n_(S), which determines the rotation speedn₁₂ of the sun gear 12. According to the above description, from thisdiagram in similar manner the driven-side vehicle drive shaft rotationspeed n_(F) can be determined.

[0056] The braking of the start-up brake S is continued, until itsrotational speed n_(S) and therewith also the sun gear rotation speedn₁₂ of the input planetary drive 4 reaches a speed of zero.

[0057] Therewith the planet arm rotation speed n₁₅ of the inputplanetary drive 4 increases to the maximum value n₁₅, _(max.) as a fixedrelation to the motor rotation speed n_(M). The vehicle drive shaftrotation speed n_(F) as driven rotational speed of the automatictransmission 26 reaches the relative value to the motor rotation speedn_(M) corresponding to the translation ratio in the first gear.

[0058] Reference Number List

[0059]1 drive shaft

[0060]2 driven shaft

[0061]3 hydrodynamic converter

[0062]4 input planetary drive

[0063]5 output planetary drive

[0064]6 converter bridging clutch

[0065]7 transmission or gear box housing

[0066]8 pump gear

[0067]9 turbine gear

[0068]10 guide wheel or impeller

[0069]11 free wheel

[0070]12 sun gear

[0071]13 planetary gear

[0072]14 internal gear

[0073]15 planet arm/planetary carrier

[0074]16 sun gear

[0075]17 internal planetary gear

[0076]18 external planetary gear

[0077]19 internal gear

[0078]20 sun gear

[0079]21 internal planet arm/internal planetary carrier

[0080]22 external planet arm/external planetary carrier

[0081]23 degree of translation

[0082]24 degree of translation

[0083]25 Lepelletier automatic transmission

[0084]26 Lepelletier automatic transmission

[0085]27 upstream or introducing or receiving reduction stage

[0086] A clutch

[0087] B clutch

[0088] C brake

[0089] D brake

[0090] E clutch

[0091] F vehicle drive shaft

[0092] M motor shaft

[0093] S start-up brake

[0094] n_(S) rotational speed of start-up brake

[0095] n_(M) motor rotation speed

[0096] n_(F) vehicle drive shaft rotation speed

[0097] n₁₂ sun gear rotation speed

[0098] n₁₄ internal gear rotation speed

[0099] n₁₄ planet arm rotation speed

[0100] n_(15, max) maximal planet arm rotation speed

[0101] n₁₆ sun gear rotation speed

[0102] n₂₁ internal planet arm rotation speed

[0103] n₂₂ external planet arm rotation speed

[0104] n₁₉ internal gear rotation speed

[0105] i_(o) degree of translation

[0106] T_(S) rotation speed of the start-up brake

[0107] T_(M) gear box input torque

1. Device for starting up a vehicle equipped with an automatictransmission provided between a drive shaft (1) and a driven shaft (2)in a transmission housing (7) with a planetary gear (4) with a firstgear (14) coupleable with the drive shaft (1), with a second gear (13,15) coupleable with the driven shaft (2) and with a third gear (12),thereby characterized, that the third gear (12) is coupleable with thetransmission housing (7) via a start-up brake (S), of which the brakeforce is controllable.
 2. Device according to claim 1, therebycharacterized, that the planetary gear is a simple planetary gear (4)with one sun gear (12) at least one planetary gear (13) and an internalgear (14), wherein the first gear is the internal gear (14), the secondgear is the planetary gear (13) and the third gear is the sun gear (14).3. Device according to one of claims 1 or 2, thereby characterized, thatthe planetary gear (4) is a component of the automatic transmission(26).
 4. Device according to claim 3, thereby characterized, that theplanetary gear (4) is a previously in-place reduction gear stage (27) ora previously in-place step up stage of the automatic transmission (26).5. Device according to claim 3 or 4, thereby characterized, that theautomatic transmission is a vehicle automatic transmission (26)according to Lepelletier.
 6. Device according to one of the precedingclaims, thereby characterized, that the start-up brake is a frictionbrake (S), with controllable slip.
 7. Device according to one of thepreceding claims, thereby characterized, that the brake force of thestart-up brake (S) is controllable in such a manner, that the brakeforce at the beginning of the start-up process is smaller than at theend of the start-up process.
 8. Device according to claim 7, therebycharacterized, that the brake force of the start-up brake (S) iscontrollable in such a manner, that the brake force at the beginning ofthe start-up process essentially disappears and that the start-up brake(S) at the end of the start-up process is arrested or is controlled forminimum slippage.
 9. Device according to one of claims 7 or 8, therebycharacterized, that the start-up element of the transmission iscontrollable by the brake force of the start-up brake (S) in such amanner, that the start-up acceleration from the beginning of thestart-up process until the end of the start-up process is freelycontrollable by a regulator.
 10. Device according to one of claims 7, 8or 9, thereby characterized, that the brake force of the start-up brake(S) is controllable from outside the transmission.
 11. Automatictransmission (26), with a device (4, S) according to one of thepreceding claims.
 12. Process for operation of a device for starting upaccording to one of claims 1 through 6, thereby characterized, that thedriven rotation speed (N₁₉, n_(F)) of the automatic transmission brakeforce of the start-up brake (S) is controlled in such a manner, that itis smaller at the beginning of the start-up process than at the end ofthe start-up process.
 13. Process according to claim 12, therebycharacterized, that brake force of the start-up brake (S) iscontrollable in such a manner, that the brake force at the beginning ofthe start-up process essentially disappears and that the start-up brakeat the end of the start-up process locks or is controlled for minimalslippage.
 14. Process according to claim 12 or 13, therebycharacterized, that the start-up element of the transmission iscontrollable via the brake force of the start-up brake (S) in such amanner, that the start-up acceleration from the beginning of the startprocess to the end of the start-up process is freely selectable orcontrollable via a regulator.
 15. Process according to one of claims 12through 14, thereby characterized, that the brake force of the start-upbrake (S) is controllable in such a manner, that the increase in therotational speed n_(F) of the driven shaft (2) follows a pre-determinedpattern.